This page carries my 'personal' experience (as on 19/10/2009) with the below-mentioned TTS (text-2-speech) softwares/tools. I have tested out these tools with respect to Tamil language alone, as of now.

The value of the following tools for educational presentations (and kind) and especially their help for the sight-impaired is immeasurable. Words can't describe their worth for the sight-impaired. For the sight-impaired, any sound is worth gold and they might probably easily get accustomed and understand each and every word, phrase, sentence and paragraph (with any of the softwares listed below). These tools are bound to improve in the future and become more and more perfect. My immense thanks to the authors of all these tools and my humble salutes to the efforts put in by these authors and the people behind 'Microsoft Speech API - SAPI', which SAPI probably is the underlying base for some/many of the available text-2-speech softwares. My comments/notes/observations in this page need not be construed by you as final/accurate. As and when your time/interest permits, please test out the following tools yourselves and form your own set of conclusions.

Regarding Azhagi's initiative in Tamil 'Text to Speech', since 2001, please see http://azhagi.com/sath.html#tts.

kind regards
viswanathan, love all serve all, www.azhagi.com

1. IISC Demo (http://mile.ee.iisc.ernet.in:8080/tts_demo)
Pros:
  • Sounds quite native and hence more understandable. This is a major advantage which can outweigh the limitations below.
  • I tried with normal colloquial Tamil and with text-book Tamil. The speech's understandability was 'very good' to 'good'.
  • Supports 'Kannada' text-2-speech too.
    Limitations:
  • Have to access the net every time.
  • The speech file (in .wav format) has to be downloaded every time. Even for 2 paragraphs of Unicode text (around 1400 characters), the file size was around 5Mb.
  • Interrupts now and then during the speech which makes the understandability look difficult which is otherwise very good.
  • Intermixed English words/phrases, if any, are left out without speech conversion.
  • With literary Tamil, it was quite difficult to understand the speech.
    Note:
    Thanks to those who sponsor(ed) this IISC project.
    Wish-List:
    I pray those instrumental for this project to release this as a free stand-alone software (without the need to access the net) or even as a DLL plugin so that it can be easily integrated by all existing Tamil softwares, which will be of ultimate benefit, esp. to the sight-impaired. Keeping the sight-impaired in mind, I wish my wish becomes a reality sooner than later. I recently received a letter from a bank manager (mentioning his active involvement in helping out the sight-impaired) who emphasised the urgent need for a software which integrates the task of reading/scanning any Tamil text in any encoding/magazine, converting it to Unicode text (if necessary) and reading it out, all in one shot, so that the need for the sight-impaired to seek others' help is as less as possible.

    2. eSpeak (http://espeak.sourceforge.net)
    Pros:
  • It is installable in your computer. So, no need to access the internet every time.
  • It is open-source. It has a DLL plugin I suppose (yet to explore more on this), which can be integrated into existing softwares.
  • All text (Tamil text has to be in Unicode) is converted to speech, including intermixed English texts.
  • Supports text-2-speech for various other world languages too, including 'Hindi'.
  • If you are computer-savvy, then there are lot of options which you can set/tweak (externally too) by which you can improve the voice quality. In this context, one may visit the pages http://espeak.sourceforge.net/phontab.html and http://espeak.sourceforge.net/languages.html
  • With the SAPI TTSapp provided for testing, you can save the copied Unicode text to a wav file. You can play that wav file in TTSapp itself or in any other sound player (Winamp, etc.)
  • You can opt to write to the author (Jonathan Duddington) - his email id is given at the top of 'http://espeak.sourceforge.net', and participate to improve his program and voice quality of Tamil or other languages. In this context, please see what the author has to say at: 'http://espeak.sourceforge.net/add_language.html' (ADDING OR IMPROVING A LANGUAGE) and 'http://espeak.sourceforge.net/languages.html' (HELP NEEDED).
  • Active forums are also available under different topics - http://sourceforge.net/projects/espeak/forums
    Limitations:
  • The speech does not sound native and hence less understandable. But, as said above, you can opt to volunteer to help out the Author.
  • While hearing the speech, as long I was seeing the original text alongwith, the speech sounded somewhat understandable. But, if I copied and heard a text which I had not read earlier, I found it difficult to understand the speech, except undertanding a word or phrase here and there.
  • With literary Tamil, it was quite difficult to understand the speech.
    Special Note:
  • To reduce the speed of the speech, you can move the slider to the left (as much as you want) in the 'Rate' slider of TTSapp.
  • In order for eSpeak to speak out Tamil Unicode text, I had to add atleast 'ta' during installation of eSpeak itself. I added the following, while installing eSpeak:
    ta+m1 ta+m2 ta+m3 ta+m4 ta+m5 ta+f1 ta+f2 ta+f3 ta+f4
    ta+croak ta+wisper
    Please see snapshot below to know in which screen I added the above. If you missed to add them during installation, no problem. You can reinstall and add them in the appropriate screen.


    3. Osai - Part of Kural software's 'Kavidhai' cheyali (http://kuralsoft.com)
    Pros:
  • It is installable in your computer. So, no need to access the internet every time.
  • As per information in kuralsoft site, speech conversion is possible for a few encodings other than Unicode too. (In my testing, it did not work with Unicode. Possibly, I made some mistake while testing with Unicode.)
    Limitations:
  • The speech does not sound native and hence less understandable.
  • English words/phrases, if any, are left out without speech conversion.
  • With literary Tamil, it was quite difficult to understand the speech.
  • I could not find a way to save the speech, to hear it later.
  • While hearing the speech, as long I was seeing the original text alongwith, the speech sounded somewhat understandable. But, if I copied and heard a text which I had not read earlier, I found it difficult to understand the speech, except undertanding a word or phrase here and there.
    Note:
    I have seen this feature in 'Kural' software as early as 2004 itself.